In many applications, electric discharge machining is used for the mass production of parts which must be machined to close tolerances. There are several factors which affect the repeatability of accuracy of machining by the EDM process including the process parameters of electrode size, spark energy, spark current, gap length, gap voltage and the wire guide used to direct the electrode to a workpiece. For example, when the EDM process is used to machine a small hole through a thin plate, the small dimensions of the wire electrode require a support system which is sufficiently accurate to support the electrode in all directions. Also, mechanical or electrical vibrations in the electrode system can result in variation in hole diameters. In the case of wire guides for directing electrodes with respect to an orifice plate for fuel injectors, for example, the electrode, even though closely guided, can vibrate in a manner so that accuracy in hole diameter cannot be achieved uniformly.
Accordingly, there is a need for obtaining improved uniformity and accuracy in guiding an electrode wire in EDM apparatus. Further, it should be achieved without affecting the various other parameters involved in improving accuracy of the EDM process.
A general object of this invention is to provide an improved wire guide for use in apparatus for electric discharge machining to obtain a high degree of repeatable accuracy in the machining of parts.